The field of surveying requires the accurate measurement of both horizontal and vertical data in the X, Y, and Z axes of the standard three-dimensional Cartesian coordinate system. The plumb bob, the level, and the transit have long been used to obtain such data. More recent technology utilizing global positioning system (GPS) methods of surveying increases both accuracy and efficiency of obtaining data. Maintaining accurate vertical plumb in field surveying, particularly when in mobile operation, is critical to obtaining accurate data. Previous patents exist for various plumb bob apparatus and leveling devices. However, these patents do not involve or suggest a device or method to automatically maintain a surveying or data collection target in a vertical plumb position that also compensates for changes in the position of the device, particularly when survey or other data is collected while the device is being moved or in mobile operation.
Several devices and approaches have been developed to improve measurement efficiency in surveying. U.S. Pat. No. 6,633,256 provides for a method and system for measuring coordinates of a target and involves manual, stationary collection of data. Other devices and methods that provide automatic plumb and level involve mechanisms using visible laser diodes, light beams, and acoustic signals (U.S. Pat. Nos. 5,619,802; 5,541,727; 5,524,352; 5,459,932; 5,287,627; 5,182,863; and 5,075,977). Still other devices involve projected light for leveling and plumbing functions for construction use (U.S. Pat. Nos. 6,625,895; 6,028,665; and 5,184,406). U.S. Pat. No. 6,594,912 provides an electronic plumb indicator for monopoles, survey poles, and GPS antennas to increase speed and accuracy at which surveying poles and GPS antenna poles are plumbed to vertical positions.
These devices, tools, and methods do not necessarily provide for maintaining a surveying or data collection antenna, target, or equipment in a vertical plumb position while in the field and particularly while in motion. The present invention provides effectively instantaneous and continuous vertical plumb and effectively constant height above ground for a data collection target or reflector while the device and vehicle to which it is mounted are stationary or are constantly changing horizontal and vertical positions in the field while in motion. Previous devices and methods do not necessarily provide accurate, efficient, safe, or timely collection of field survey data and effectively instantaneous and continuous vertical plumb and effectively constant height above ground for the target antenna or reflector while in motion as does the present invention.
Although known methods exist to improve measurement efficiency in surveying and to vertically plumb targets, it remains a significant goal of those skilled in the art to devise a simple device and method to specifically provide automatic or self vertical plumbing of a surveying target or reflector or other equipment requiring vertical plumb in field applications, to provide accurate, efficient, and safe collection of data thereby, and to provide such automatic vertical or self plumbing of the target particularly while such device and target are either stationary or in motion. The present inventors have designed a device and method for these purposes.